The present invention relates to processes for the preparation of highly branched functional and reactive polymers. Specifically, the present invention relates to novel highly branched functional and reactive polyesters prepared through a one-step process.
Highly branched polymers can be made by multi-step or one step process. Multi-step generation processes were exemplified by Frechet in U.S. Pat. No. 5,041,516 and by Hult in U.S. Pat. No. 5,418,301. Both patents described that the highly branched polymers known as dendrimer or xe2x80x9cstarburst polymerxe2x80x9d were made through a series of growth steps consisting of repeatedly reacting, isolating, and purifying.
One-step process was first conceptualized by Flory (J. Am. Chem. Soc., 74, p2718 (1952)) who demonstrated by theoretical analysis that a highly branched and soluble polymers could be formed from one-step condensation polymerization of monomer comprising the structure AB2, where A and B are reactive groups. In contrast to the dendrimers, the polymer formed by AB2, polymerization is randomly branched. Kim et al in U.S. Pat. No. 4,857,630 disclosed that hyperbranched polyphenylenes can be prepared by one-step polymerization of AB2-type monomers such as (3,5-dibromophenyl)boronic acid and 3,5-dihalophenyl Grignard reagents. Baker in U.S. Pat. No. 3,669,939 described that highly branched aliphatic polyesters could be prepared by one-step melt condensation polymerization of monomers having a single carboxylic acid and multiple alcohols. Hawker et al disclosed that all aromatic, highly branched polyesters can be made by melt polymerization of 3,5-bis(trimethylsiloxy)benzoyl chloride (J. Am. Chem. Soc., 113, p4583 (1991)). U.S. Pat. No. 5,196,502 discloses the use of diacetoxybenzonic acids and monoacetoxydibenzonic acids to produce wholly aromatic polyesters. U.S. Pat. Nos. 5,225,522 and 5,227,462 disclose highly branched aliphatic-aromatic polyesters and processes for making the same. U.S. Pat. No. 5,418,301 discloses a process for preparing dendritic macromolecules. U.S. Pat. No. 5,514,764 discloses preparation of hyperbranched polyester by a one-step process of polymerizing a monomer of the formula A-R-B2. U.S. Pat. No. 5,567,795 discloses synthesis of highly branched polymers in a single processing step by using branching aromatic monomers and an end-capping monomer. U.S. Pat. No. 5,663,247 disclosed a hyperbranched macromolecule of polyester type comprising a central monomeric or polymeric epoxide group containing nucleus and at least one generation of a branching chain extender having at least three reactive sites of which at least one is a hydroxyl or hydroxyalkyl substituted hrodroxyl group and at least one is a carboxyl or terminal epoxide group and the process for making the same.
Most AB2 type monomers, however, are not commercially available, and access to such monomers accordingly involves synthetic efforts, which is potentially problematic, especially on a large scale. To cope with such problem, an A2+B3 approach to hyperbranched polymers has been recently revisited. In A2+B3 polymerization, di- and tri-functional monomers are reacted together. For ideal A2+B3 polymerization, intramolecular cyclization must be minimized as a competing and chain terminating process during polymer propagation, all A groups and all B groups should have near equal reactivity in both the monomers as well as the growing polymers, and the A and B groups should have exclusive reactivity with each other. In view of such requirements, relatively few specific combinations of A2+B3 polymerization schemes have been proposed. Jikei et al (Macromolecules, 32, 2061 (1999)), e.g., has reported synthesis of hyperbranched aromatic polyamides from aromatic diamines and trimesic acid. Emrick et al (Macromolecules, 32, 6380 (1999)) has disclosed the synthesis of hyperbranched aliphatic polyethers by means of proton-transfer polymerization of 1,2,7,8-diepoxyoctane as A2 monomer and 1,1,1-tris(hydroxymethyl)ethane as B3 monomer.
It is known that ring open reaction between terminal epoxides with acid chlorides, in the presence of tetrabutylammonium bromide, can form an anti-Markinovkov ester product containing a primary chloride. This reaction was applied to dicpoxides and diacid chlorides to form polyesters (Kameyama et al., Macromolecules 25, p.2307 (1992)). However, no prior art teaches the use of multiple epoxides and multiple acid chlorides to prepare highly branched polymers.
It would be desirable to provide a process for producing highly branched polyesters of high molecular weight without requiring the use of AB2 type monomers or multi-step reactions and purification.
It would be further desirable to provide a process which results in highly branched polyesters having a multiplicity of very reactive epoxy or acid chloride groups or both on the outside surface which can be further converted to other functional groups.
In accordance with one embodiment of the invention, a polymerization process for producing highly branched polyesters is disclosed comprising reacting a multi-functional di- or higher epoxide group containing compound with a multi-functional di- or higher acid chloride group containing compound, wherein at least one of the epoxide or acid chloride group containing compounds is a tri- or higher epoxide or acid chloride group containing compound.
The invention provides a process for producing highly branched polyesters in one reaction step. The present process comprises a ring opening reaction between a reactant or reactants having multiple epoxide groups and another reactant or reactants having multiple acid chloride groups. The invention has the capability of making highly branched structures of high molecular weight and has the advantages of not requiring multi-step reactions and purification. The invention yields highly branched polyesters having a multiplicity of very reactive epoxy or acid chloride or both on the outside surface which can be further converted to other functional groups, including polymerizable groups and initiating groups, which can undergo further chain extensions.
The present invention is directed to prepare a highly branched polyester in a single step procedure. The present process utilizes the ring opening reaction of multiple epoxide group containing compounds with multiple acid chloride group containing compounds at a sufficient temperature and for a sufficient period of time to produce a highly branched macromolecule of the polyester type. In accordance with the invention, the use of compounds having multiple reactive epoxide groups in combination with compounds having multiple acid chloride reactive groups has been found to be an especially useful path to providing highly branched polyester materials. The acid chloride groups are in general more reactive than carboxylic acid groups, and the reaction between acid chloride and epoxide groups proceeds under generally less stringent conditions than epoxides and carboxylic acid groups. Further, the acid chloride and epoxide groups can advantageously directly provide highly reactive end groups in the resulting highly branched polymers.
Compounds with multiple reactive epoxide groups which may be used in the process of the invention can be represented by the following formula (I): 
and compounds with multiple reactive acid chloride groups which may be used in the process of the invention can be represented by the following formula (II): 
where R1 and R2 are each independently a monomeric, oligomeric, or polymeric compound nucleus, and n and m are integers between 2 and 100, preferably between 2 and 20, without n and m being 2 at the same time. Each R1 and R2 compound nucleus may comprise, e.g., a straight or branched alkyl, cycloalkyl, aryl or alkylaryl moiety, or an oligomeric or polymeric chain.
In specific embodiments, the multifunctional epoxide group containing compound may be selected from glycidyl esters and ethers of the following formulas (Ia) and (Ib): 
Examples of multiple reactive epoxide group containing compounds include but are not limited to: di or triglycidyl isocyanurate, triphenylolmethane triglycidyl ether, di or triglycidylaniline, N,N-diglycidyl-4-glycidyloxyaniline, 1,2-epoxy-3-allyloxypropane, 1,2-epoxy-3-phenoxypropane, diglycidyl terephthalate, epoxidized soybean fatty acid or oil, epoxidized polyvinylalcohol, poly(glycidyl (meth)acrylates) based homo and copolymers, epoxy resins such as 3,4-epoxy-cyclohexyl methyl 3,4-epoxy cyclohexane, trimethylolethane triglycidyl ether, trimethylopropane triglycidyl ether, poly(dimethyl siloxane) diglycidyl ether, poly(propylene glycol)diglycidyl ether, poly(ethylene glycol) diglycidyl ether, poly[(o-eresyl glycidyl ether)-co-formaldehyde].
Example of multiple reactive acid chloride group containing compounds include but are not limited to: 1,3,6-benzenetricarbonyl trichloride, succinyl chloride, terephthaloyl chloride, malonyl chloride, poly (meth)acryloyl chloride.
Scheme 1 shows an example of the formation of a highly branched polyester in accordance with the invention by reacting triphenylolmethane triglycidyl ether with terephthaloyl chloride: 
Catalysts may be used to facilitate reaction between the epoxide and acid chloride groups. Preferred catalysts for use in the process of the invention inculde onium salts, polyethers and cryptand based complexes, and amine containing Lewis bases.
Preferred omium salts for use as catalysts inculde but are not limited to: Me4N+Brxe2x88x92, Pr4N+Brxe2x88x92, Bu4N+Brxe2x88x92, Bu4P+Brxe2x88x92, Bu4N+Clxe2x88x92, Bu4N+Fxe2x88x92, Bu4N+Ixe2x88x92, Bu4P+Clxe2x88x92, (C8H17)3NMe+Clxe2x88x92, (C8H17)3PEt+Brxe2x88x92, C6H13NEt3+Brxe2x88x92, C7H17NEt3+Brxe2x88x92, C10H20NEt3+Brxe2x88x92, C12H25NEt3+Brxe2x88x92, C16H33NEt3+Brxe2x88x92, C6H13PEt3xe2x88x92Brxe2x88x92, C6H5CH2NEt3+Brxe2x88x92, C16H33PMe3+Brxe2x88x92, (C6H5)4P+Brxe2x88x92, (C6H5)4As+Clxe2x88x92, (C6H5)4As+Brxe2x88x92, (C6H5)3PMe+Brxe2x88x92, (HOCH2CH2)3NBu+Br, Bu4N+OHxe2x88x92, Bu4N+(ClCrO3)xe2x88x92, Bu4N+CNxe2x88x92, Bu4N+BH3CNxe2x88x92, Bu4N+(H2PO4)xe2x88x92, Bu4N+(H2PO2)xe2x88x92, Bu4N+1/2(PtCl6)xe2x88x92, Bu4N+PF6xe2x88x92, Bu4N+HSO4xe2x88x92, Bu4N+[CH3CH(OH)CO2]xe2x88x92, Bu4N+NO3xe2x88x92, Bu4N+IO4xe2x88x92, Bu4N+ReO4xe2x88x92, Bu4N+BF4xe2x88x92, Bu4N+[B(C6H5)4]xe2x88x92, Bu4N+[CF3SO3]xe2x88x92, 
R3xe2x80x94N+(CH2)2-4O(CH2)2-4N+R3, Brxe2x88x92(Clxe2x88x92) [where R represents alkyl group]
Any polyethers or cryptand based complexes which can facilitate the reaction can be used in the present invention as catalyst. Examples of these compounds include but are not limited to polyethylene glycol and derivatives such as HO(CH2CH2O)nH (n=2-600), RO(CH2CH2O)H where R=C1 to C3 alkyl groups, N(CH2CH2OCH2CH2OCH3)3, N(CH2CH2OCH2CH2OH)3, crown ethers and cryptands such as 18-crown-5, 15-crown-5, dibenzo-18-crown-6, dicyclohexano-18-crown-6, Kryptand 211, Kryptanid 222, Kryptand 221.
Any amine containing Lewis bases can also be used in the present invention. Example of these Lewis bases are but not limited to trialkyl substituted amine, pyridine, dimethylaminopyridine.
The amount of catalyst used in the present invention can preferably vary from 0.1% to 30%, more preferably from 0.1% to 10%, and most preferably from 0.1% to 2%, based on the monomer molar concentration.
In a specific embodiment, the resultant highly branched polymers prepared according to the present invention have a multiplicity (e.g., represented by x in Scheme 2 below) of either epoxy or acid chloride or both functional groups on the outside surface. The resulting functional groups on the highly branched polymer surface will depend on polymerization conditions such as the molar ratio of epoxide to acid chloride, monomer concentration, catalyst, polymerization temperature and time, and the like. In preferred embodiments, the reactant concentrations are selected to provide a ratio of epoxide groups to acid chloride groups for the polymerization reaction of greater than 2:1 (resulting in primarily epoxide terminated products) or less than 2:3 (resulting in primarily acid chloride terminated products), as ratios closer to 1:1 (e.g., from about 2:3 to 2:1) have been found to be more prone to crosslinking and gel formation.
In another embodiment, the epoxy or acid chloride groups on the surface of polymer can be easily converted to other types of functional groups by means of organic reactions. Examples of these functional groups include but are not limited to water soluble/dispersible groups, crosslinking groups such as vinyls, initiating and polymerizable groups for further chain extensions, imaging and photographically useful groups such as dyes and couplers, bio-compatible groups, and the like. For example, acid chloride or epoxy end groups can be easily converted into hydrophilic groups such as xe2x80x94NH2, xe2x80x94COOH, xe2x80x94SO3H, xe2x80x94OH, xe2x80x94N+R3, and the like as illustrated in Scheme 2. 
Also, highly branched polymers with various photographically useful end groups as described in copending application U.S. Ser. No. 09/132,045, the disclosure of which is incorporated by reference, can be made via the present invention. For example, a polymeric magenta coupler can be formed as in Scheme 3. 
Similarly other types of functional polymers such as surface active polyesters, heat (temperature, pH, and the like)-sensitive smart polyesters, light or electron harvesting polymers, etc., can be obtained.
The functional hyperbranched polymers can also be used for further chain extension to form polymers with higher molecular weight and even more complex architectures. There are two ways to make chain extension.
First, one or more initiating sites can be introduced into the end of hyperbranched polyester. These macroinitiators can be used in any kinds of living and non-living chain polymerizations such as radical, anionic, cationic, group transfer polymerization, atom transfer radical polymerization, telomerization, coordination polymerization, and the like to form polymers with more complex architectures such as star polymers with polyester cores, hyperbranched polyesters based block/graft/super branched polymers and the like. Thus, the present invention provides a method to make even complex polymers or copolymers comprising polyesters and vinyl polymers in the same molecule.
For example, a macroinitiator for Atom Transfer Radical Polymerization (ATRP, as described, e.g., in U.S. Pat. Nos. 5,789,487 and 5,807,937, the disclosures of which are incorporated by reference) can be made by modification of epoxy ended highly branched polymer with trichloroacetyl chloride (Scheme 4) and can be used in ATRP of methyl methacrylate (Scheme 5): 
Alternatively, epoxy and acid chloride ended hyperbranched polyesters can react with any mono- or multiple functional monomers such as amine, OH, epoxy, acid chloride containing condensation type of monomers to form even more complex polymers or copolymers.
For example, the reaction between multiple acid chloride ended hyperbranched polyester and diepoxides yields a highly branched polyesters with higher molecular weight (Scheme 6). 
(where G2, G3, G4, . . . represents second, third, fourth, etc. generations).
As another example, the reaction between multiple acid chloride ended hyperbranched polyester and mono NH2 containing polyether compounds such as Jeffamine(trademark) (Huntsman) compounds may result in hydrophiphilic star copolymer with highly branched polyester as the core and Jeffamine(trademark) as the branches.
The present polymerization process may be conducted as bulk polymerization, i.e., in absence of solvent. However, it can also be carried out in any solvent, which might include but are not limited to ethers, cyclic ethers, alkanes, cycloalkanes which may be substituted, aromatic solvents, halogenated hydrocarbon solvents, acetonitrile, dimethylformamide, ethylene carbonate, dimetliylsulfoxide, dimethylsulfone, sulfolane, alcohol, water, mixture of such solvents, and supercritical solvents such as carbon dioxide, alkanes in which any H may be replaced with F, etc. Preferred solvents include toluene, cyclohexanone, anisole, o-dichlorobenzene, DMF, sulfolane, ethyl benzene.
The present process may also be conducted in accordance with known suspension, emulsion, microemulsion, gas phase, dispersion, precipitation, template, reactive injection molding, phase transfer polymerization processes, melting polymerization, and the like.
The polymerization can be conducted in accordance with known batch, semi-batch, continuing processes, tube-flow, and the like. The polymerization temperature can be varied from xe2x88x92200 to 500xc2x0 C., more typically from xe2x88x92100 to 200xc2x0 C., and preferably from 20 to 120xc2x0 C. Polymerization pressure may typically vary from 10xe2x88x928 atm to 10xe2x88x923 atm. Combinatorial chemistry and experimental design can be used in the context of the present invention to optimize the polymerization reaction conditions.
The molecular weight and molecular distribution of polymers prepared in accordance with the present invention may vary from about 100 to 10xe2x88x928 and from 1.001 to 100, respectively, and the glass transition temperatures from xe2x88x92300 to 1000xc2x0 C. depending upon the polmerization reactant compositions.
The final polymers can be purified with known processes such as precipitation, extraction, and the like. Polymers can be used in the forms of solid particle, solution, dispersion, latex, and the like.
The highly branched polymers and copolymers prepared in the present invention can be used in a variety of applications such as plastics, elastomers, fibers, engineering resins, coatings, paints, adhesives, asphalt modifiers, detergents, diagnostic agents and supports, dispersants, emulsifiers, rheology modifiers, viscosity modifiers, in ink and imaging compositions, as leather and cements additives, lubricants, surfactants, as paper additives, as intermediates for chain extensions such as polyurethanes, as additives in ink jet, printing, optical storage, photography, photoresist, and coloration of polymer, as water treatment chemicals, cosmetics, hair products, personal care products, polymeric dyes, polymeric couplers, polymeric developers, antistatic agents, in food and beverage packaging, pharmaceuticals, carriers for drug and biological materials, slow release agent formulations, crosslinking agents, foams, deodorants, porosity control agents, complexing and chelating agents, carriers for chiral resolution agents, catalysts, carriers for gene transfection, for encapsolation, as light harvesting materials, as non-linear optical materials, and to form super macromolecular assemble.